Papermaking drainage fabric and stock inlet combination for producing even edged paper web

ABSTRACT

In the paper forming art an arrangement of a stock slurry inlet and a belt of drainage fabric; the drainage fabric has liquid impermeable bands positioned inwardly of its side edges and the inlet discharges the stock slurry onto the fabric including the bands. The effect of the bands is to terminate the formed paper web sidewardly along the inner edges of the bands and to provide edges of the sheet which need not be trimmed. The arrangement has particular utility where sheet formation is between two fabrics and there is little room for positioning the usual flow restricting shoes, and is advantageous also in providing for uniform basis weight across the sheet width. The liquid impermeable bands may be one-fourth to three-eighths inches in width and the side edges may be 1 to 2 inches in width.

States Patent Peterson 145 Mar. 28, 1972 1 IPAIPIERMAKING DRAINAGE FABRIC 3,360,428 12/1967 Loynd ..162/347 AND STOCK INLET COMBINATION 2,207,609 7/1940 Buchanan ..139/425 A PRUDUCING EVEN EDGED PAPER FOREIGN PATENTS OR APPLICATIONS H16,726 3/1956 Germany ..162/DIG. 1 [72] Inventor: LeRoy L. Peterson, Neenah, Wis.

[73] Assignec: Kimberly-Clark Corporation, Neenah, 'f' Examiner's Bashore Assistant Examiner-Alfred DAndrea, Jr.

AttorneyDanic1 J. Hanlon, Jr. and Raymond J. Miller [22] Filed: Feb. 10, 1970 21 Appl. No.: 10,239 [57] ABSTRACT In the paper forming art an arrangement of a stock slurry inlet Related Application Data I and a belt of drainage fabric; the drainage fabric has liquid im [63] Continuation-impart of Ser. No. 566,281, July 19, permeable bands positioned inwardly of its side edges and the 1966, abandgned, inlet discharges the stock slurry onto the fabric including the bands. The effect of the bands is to terminate the formed [52] 11.1.8. Cl. ..l62/303, 117/44, 139/425 A, paper Web sidewardly along the inner edges of the bands and 140/24, 161/89, 161/149, 162/351, 162/DIG. l, to provide edges of the sheet which need not be trimmed. The 245/8 arrangement has particular utility where sheet formation is [51] int. Cl ..D2lf l/00, D2lf 1/10, D2 11 7/08 between two fabrics and there is little room for positioning the [58] lField of Search ..162/318, 334, 345, 346, 347, usual flow restricting shoes, and is advantageous also in 162/351, 352, 353, 358, DIG. 1, 348; 161/147, 149, providing for uniform basis weight across the sheet width. The 88, 89; 140/14, 22, 24; 1 17/43, 44; 139/425, 425 A; liquid impermeable bands may be one-fourth to three-eighths 245/8 inches in width and the side edges may be 1 to 2 inches in width. [56] References Cited 5 Claims, 4 Drawing Figures UNITED STATES PATENTS 2,659,958 11/1953 Johnson ..,.,....16 2/D1G. 1

PATENTEDMAR28 I972 3,652,390

sum 2 OF 2 FIG. 4

PAPERMAKING DRAINAGE FABRIC AND STOCK INLET COMBINATION FOR PRODUCING EVEN EDGED PAPER WEB This application is a continuation-in-part of my copending application Ser. No. 566,281 filed July 19, 1966 now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to papermaking apparatus and more particularly to the draining fabric on which paper stock is deposited for forming a web on the fabric.

Conventional Fourdrinier papermaking machines for lightweight paper or tissue, in particular, generally utilize flow restricting shoes on sides of the area of the Fourdrinier fabric on which web formation takes place for limiting the sideward extent to which the stock may flow on the fabric and for thus limiting the web in width. In addition, fine water jets are utilized for cutting longitudinal channels on the edges of the web as it is being dewatered on the fabric so as to thereby provide trimmed web edges, which are apparent particularly after the web has been dewatered and dried to form finished tissue. The I edges of paper tissue webs formed in this manner, however, are typically rather irregular and the webs have a narrow, relatively heavy basis weight zone at each edge, since the water jets move the paper fibers of the web in both directions trans versely of the web as the jets pierce the web. The variable basis weight of the tissue at the web edges necessitates trimming of the web and consequent waste of paper or, if no trimming is done, web breaks and other problems during subsequent calendering or other finishing operations are caused, particularly in the case of tissue which is creped off the drier of the papermaking machine and which is subsequently restretched longitudinally to some extent in making the tissue limp, such as for facial usage.

2. Object of the Invention It is an object of the present invention to provide an improved mechanism in a papermaking machine capable of making straight even edges on a paper web without rendering the basis weight nonuniform, to eliminate the necessity of trimming and overcoming the problem of breaks in subsequent converting due to the irregular basis weight at the sheet edges. In brief, the invention contemplates the provision of a papermaking forming wire which has its interstices filled with plastic or other filler in longitudinal bands inwardly of side edges of the drainage fabric for preventing the drainage of paper stock through the fabric along these bands and for thereby terminating the formed paper web along the inner edges of the bands.

BRIEF DESCRIPTIONv OF THE DRAWINGS The invention consists of the novel constructions to be hereinafter described and claimed for carrying out the above mentioned objects, and such other objects, as will be apparent from the following description of preferred forms of the invention, illustrated with reference to the accompanying drawings, in which the same reference characters designate the same parts. In the drawings:

FIG. 1 is a diagrammatic elevational view of the wet end of a Fourdrinier papermaking machine and including a paper stock inlet discharging between the top pair of a series of three rolls disposed one above the other; 4

FIG. 2 is a diagrammatic elevational view on an enlarged scale of the three rolls and the stock inlet;

FIG. 3 is a fragmentary plan view of a paper forming fabric which may be used in the apparatus illustrated in FIGS. 1 and 2; and

FIG. 4 is a sectional view of the forming fabric of FIG. 3.

DETAILED DISCUSSION OF THE INVENTION Referring to FIGS. 1 and 2, the illustrated papermaking machine may be seen to comprise a Fourdrinier stock draining fabric 10 which is in the form of a continuous belt or loop and which is supported by means of a plurality of rolls 11, 12, 13, 14, 15, 16 and 17. The fabric 10, in accordance with conventional practice, is suitably made up of interwoven warp and weft filaments extending in the machine direction or in the direction indicated in FIG. 1 in which the loop of fabric 10 moves about the rolls 11 to 17. It will be noted that the rolls ll, 17 and 16 have their centers on substantially the same vertical plane, and there is a slight separation between these rolls so that the fabric bridges from left to right from the roll 11 to the roll 17 and then back again from right to left from the roll 17 to the roll 16, as these and the other rolls supporting the fabric are illustrated in FIGS. 1 and 2.

An endless felt 18 also extends around the roll 17 and is located between the fabric 10 and the exterior surface of the roll 17. The felt 18 is supported by means of a plurality of supporting rolls including the rolls 19 and 20. Suitable mechanism may be provided for dewatering the felt 18 including wringer rolls 21 and 22 having a nip between them through which the felt 18 moves.

A stock inlet 23 is provided for discharging a slurry of paper stock onto the portion of the fabric 10 bridging the rolls 11 and 17. The stock inlet 23 comprises a manifold 24 and a pair of plates 25 and 26 which have facing, parallel flat surfaces defining a slot 27 between them. It will be observed from FIGS. 1 and 2 that the slot 27 is nearly horizontally disposed so as to direct stock directly into the nip between the rolls 11 and 17.

In operation, paper stock slurry is discharged through the inlet slot 27 in a stock forming zone where the endless loops 10 and 18 approach each other; formation of a paper web takes place between the felt l8 and the fabric 10 as they pass over the roll 17. The paper web remains with the felt 18 as the fabric and felt separate below the roll 17, and the web is carried on the under side of the felt l8 and travels with the felt through conventional dewatering devices (not shown) and to a rotatable drier drum (not shown) for dewatering and drying the web for subsequent reeling.

This general type of papermaking machine, in which paper stock is discharged between a pair of rolls and in which formation takes place between a felt traveling on one of the rolls and a wire disposed over the felt and on this one roll, is described in a patent of Charles A. Lee and Charles A. Lamb, U.S.v Pat. No. 3,224,928, issued Dec. 21, 1965, and in an application of John B. Graham, Ser. No. 419,765, filed Dec. 21, 1964, now US. Pat. No. 3,400,045, and in an application of James Loynd, Ser. No. 433,934, filed Feb. 19, 1965, now US. Pat. No. 3,378,435. These patents may be referred to for further details of such a machine, and therefore it is considered that further details need not be set forth herein. Generally speaking, however, it should be noted that the stock slurry is subjected to dewatering to form the web under the influence of pressure with which the wire 10 bears on the felt and roll 17.

The fabric 10 as illustrated in FIG. 3 has a specially treated or constructed band or zone 30 which lies inwardly of each edge of the fabric 10 and serves to inhibit drainage. The longitudinally extending intermediate portion or zone 31 of the fabric 10 is untreated and is liquid pervious inasmuch as the fabric 10 is of generally conventional construction being suitably formed by warp and weft wires, such as of synthetic material or brass, for example, which are interwoven and which permit the passage of liquid through their interstices so as to form a paper web on the fabric from paper stock deposited on the fabric. The bands 30 may be formed by filling the interstices of the Fourdrinier fabric with a plastic and serve to limit the formation of the web sidewise. Such plastic may be polyethylene or as is apparent, other filling materials such as adhesive or rubber may be used instead; or, in fact, the bands 30 may be formed without such filling material and simply by weaving the fabric 10 in a very close manner along these bands, thus preventing water drainage through the bands. The warp wires of the fabric 10 in the bands 30 (the wires extending in the machine direction or longitudinally of the fabric 10) may be woven to be as close together as possible in order to secure this effect, for example. The bands 30 extend lineally and circumferentially around the drainage belt.

The paper stock from the inlet 23 drains through the interstices between the warp and weft wires and forms a paper web on the central portion 31 of the fabric in the usual manner; however, that portion of the stock which is discharged onto the bands 30 cannot drain through the fabric and, thus, does not mat and form a sideward continuation of the paper web but may only provide unconnected fibers on these bands. In view of the fact that the inner edges of the bands 30 are preferably made exactly straight, the resulting paper web has very straight, even and trimmed edges so as to eliminate the necessity of trimming or the problem of breaks in subsequent converting apparatus due to irregularities of sheet edge.

A Fourdrinier fabric of the illustrated type having the impervious side bands 30 lying inwardly predetermined distances from the edges of the fabric is particularly useful in connection with the papermaking machine of the FIG. 1 type in which the forming area is in reality between the portions of two endless loops of material which approach each other and come together as do the fabric 10 and felt 18 on the surface of the roll 17. This is in view of the fact that there is no room between these fabrics in their approaching portions to position shoes such as are ordinarily used on Fourdrinier machines having open forming areas on their foraminous forming fabrics for limiting the sideward flow of the paper stock. A forming fabric of the FIG. 3 type is also particularly suitable for use with a papermaking machine of the FIG. 1 type having the ends of the stock discharge plates and 26 positioned directly in the nip between the adjacent rolls 11 and 17, nearly in touching relationship with respect to the peripheries of the rolls 11 to 17, so that there is in reality a kind of pressure forming taking place. With this type offorming, there is a back pressure of stock created in the forming nip between the rolls 11 and 17, and this back pressure provides a sideward force on the stock tending to spread it and provide edge portions of the web that decrease gradually in basis weight from the web edges, rendering the web unsuitable for many applications without trimming, particularly those in which uniformity of basis weight from one edge to the other edge is needed.

The center portion 31 of the fabric 10 on which the bands are provided is bounded by the bands 30, and permeable zones 32 of the untreated fabric are desirably retained on the side edges ofthe fabric 10. The bands 30 may, for example, be three-eighths inch to one-quarter inch in width, and they may suitably be spaced from the side edge portions of the fabric 10 so that the side edge portions are an inch to two inches in width, for example. While the bands 30 do not allow any formation of a paper web on them due to lack of drainage through the fabric on the bands 30, paper stock does drain through the permeable zones 32 of the fabric 10 between the bands 30 and the wire edges, minimizing any tendency of the slurry to back flow to the fabric center; the isolated web portion may be easily removed as a strip of web from both the fabric 10 and the felt 18, and also from the drier drum to which the web is transferred from the felt 18. Since the inner edges of the bands 30 are straight and regular, the paper web formed on the fabric 10 has straight even edges.

Since the impermeable bands 30 provide straight even edges on the paper webs formed by the fabrics on which these bands are disposed, they minimize breakage of the webs in subsequent converting. In connection with the use of bands 30, a more uniform basis weight is secured on the edges of the webs being formed and straighter web edges are obtained than are possible using conventional water jets that displace the paper fibers sidewardly in both directions from the jets.

It is to be understood that the invention is not to be limited to the specific constructions, arrangements and devices shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

Iclaim: 1. Papermaking apparatus for making a web of fibrous material from a stock slurry of such material, said apparatus comprising a stock inlet and endless loops approaching each other adjacent the stock inlet to define therebetween a stock forming zone for the receipt of the stock slurry, one of said endless loops being a belt of drainage fabric through which the stock slurry may drain to form a web, said belt having a longitudinally extending liquid permeable center portion and longitudinally extending liquid permeable side edge portions and also having between said edge portions and said center portion bands which are substantially impermeable to liquid, said bands being located so as to limit the formation of the web sidewise of said bands but such as to provide for slurry flow over said bands to said liquid permeable side edge portions.

2. Papermaking apparatus according to claim 1 in which the liquid permeable longitudinally extending side edge portions are ofa greater width than the said impermeable bands.

3. Papermaking apparatus according to claim 1 in which the said impermeable bands are of a constant width and extend circumferentially around the drainage belt, each band having a straight edge adjacent said center portion of said belt so as to provide correspondingly straight edges on the web formed on the belt.

4 Papermaking apparatus according to claim 3 in which the said impermeable bands are at least one-fourth inch in width and are spaced inwardly of the side edge of the drainage belt to provide a side edge drainage area of at least about one inch in width.

5. Papermaking apparatus according to claim 4 in which the impermeable bands are one-fourth to three-eighths inch in width and the side edge drainage portion is between about 1 and 2 inches. 

1. Papermaking apparatus for making a web of fibrous material from a stock slurry of such material, said apparatus comprising a stock inlet and endless loops approaching each other adjacent the stock inlet to define therebetween a stock forming zone for the receipt of the stock slurry, one of said endless loops being a belt of drainage fabric through which the stock slurry may drain to form a web, said belt having a longitudinally extending liquid permeable center portion and longitudinally extending liquid permeable side edge portions and also having between said edge portions and said center portion bands which are substantially impermeable to liquid, said bands being located so as to limit the formation of the web sidewise of said bands but such as to provide for slurry flow over said bands to said liquid permeable side edge portions.
 2. Papermaking apparatus according to claim 1 in which the liquid permeable longitudinally extending side edge portions are of a greater width than the said impermeable bands.
 3. Papermaking apparatus according to claim 1 in which the said impermeable bands are of a constant width and extend circumferentially around the drainage belt, each band having a straight edge adjacent said center portion of said belt so as to provide correspondingly straight edges on the web formed on the belt.
 4. Papermaking apparatus according to claim 3 in which the said impermeable bands are at least one-fourth inch in width and are spaced inwardly of the side edge of the drainage belt to provide a side edge drainage area of at least about one inch in width.
 5. Papermaking apparatus according to claim 4 in which the impermeable bands are one-fourth to three-eighths inch in width and the side edge drainage portion is between about 1 and 2 inches. 